++++++++++++++++++++++++++++++++++++++++++++++
Date: Fri, 20 Apr 2001 12:31:43 -0700
From: "Ron D'Eau Claire"
Subject: RE: [Elecraft] KSB2 card inoperative...
Steve Banks K0PQ, asked:
"However, the wheels came off of the SSB card project...
I think what is happening basically is that the rig refuses to key on when
asked to. I also tried keying the rig manually via the mic jack and a
similar situation occurs: NOTHING! The rig will not key on at all,
apparently."
You aren't really 'keying' the rig in the Coarse Carrier Balance Adjustment.
It just runs some RF through the SSB board and feeds the signal into the
receiver so you can see it on the S-meter.
It sounds like nothing happens when you key it either, but I suspect you
need to find out why you can't feed some signal back into the RX with the
SSBA-BAL menu command first - if I understand your note correctly.
If you still have trouble with the PTT system itself after getting signal
through the SSB board for the Coarse Adjustment, try keying the rig using
the TUNE button. That would verify that the rig will key and point you
toward a problem in the PTT circuit. Next make sure you have the rig in PTT
mode, and not VOX mode. You can still key the rig with the TUNE button, but
the PTT input is inoperative in VOX.
Ron AC7AC
K2 # 1289
++++++++++++++++++++++++++++++++++++++++++
Date: Sat, 21 Apr 2001 11:22:28 -0600
From: "Steve Banks"
Subject: [Elecraft] KSB2 card inoperative..follow-up message
Ron, AC7AC-
Don, W3PFR-
Jim, K4ZM-
I thought you three folks (my apologies if I forgot to acknowledge anyone
else) might be interested to know that WE HAVE LIFTOFF! My KSB2 card now
plays very well indeed.
This morning as I continued to ponder the ineffective SSBA BAL command I
mentioned in previous posts, it occurred to me that the balanced modulator,
U5, might not even be turning ON when the BAL command was given, especially
since the rig was also not responding to PTT commands from the mic jack.
Thus, R1 had nothing to do except await a BAL signal, and it would remain
stone-cold until that happened. Several dozen voltage measurements and
close inspections later, it was obvious that there was no D.C. voltage being
applied to U5 in the transmit mode...it was napping soundly.
The air gap in the supply (MOD EN) to U5-8 was finally tracked down to
U1-13. Here's where the plot thickens, and I thought you might be
interested to know exactly what happened.
For reasons unknown to me, when I originally installed and soldered the
28-pin socket for the KSB2 U1 micro, I noticed that whisker-end of Pin 13 on
the socket failed to show up on the bottom of the RF board as its 27 sibling
pins had...hmmm...I wondered why it was absent. (Of course, I didn't notice
that until AFTER most of the pins were soldered, making its removal and
replacement of the socket a virtual impossibility!) I decided to drive on
with building the card and worry about it later if necessary. Not a good
idea.
I made a note to myself in the KSB2 manual (I take copious notes during any
building project to later jar my memory), but as a precaution at the time, I
also measured the DC resistance from the bottom side of the PCB to the U1-13
socket receptacle on the topside of the PCB. All 28 pins, including #13,
showed solid shorts as they should have. No problem, I figured...must be
okay in spite of the absent whisker on the bottom of the board.
Fast-forward to earlier this morning while still trying to get the completed
card to work.
I once again measured the DC resistance of each KSB2 U1 socket pin (with U1
itself REMOVED) to the bottom of the PCB and got the same result as
before...solid shorts, even on pin 13. Should work, I thought, but still no
explanation for the problem I was seeing with the inoperative SSBA BAL
command.
Next I reinserted the U1 chip itself back into its socket and made the same
resistance measurements, concentrating on Pin 13 where MOD EN voltage is
supposed to live. This time I measured the resistance from the "shoulder"
of Pin 13 on the chip itself to the bottom of the board with the chip fully
seated. WIDE OPEN!!! Now we're making progress.
Okay, I said, why the heck does merely reinserting the chip in its socket
cause an open circuit to occur between the top and bottom of the board that
was not there before it was plugged in? I pulled the micro out of its
socket almost all the way but left it lightly plugged in, and remeasured its
resistance to the bottom of the board. SOLID SHORT!! Now we're making even
more progress!
The U1 socket must have a fractured pin connector on its underside that is
now impossible to reach, I thought. Otherwise the chip has a bent pin that
I didn't notice (no such luck it turns out).
Only God Himself would know for sure, I thought, but I hoped that reflowing
the U1 socket Pin 13 joint with a copious bit of solder just might save the
day and close the now-invisibleair gap to the chip. (Apparently the Pin 13
lead on the underside of the socket was bent or fractured (or nearly so)
when I first installed it--no doubt my own fault--and that led to its being
open later after the chip was plugged in. Clearly, the open circuit was
intermittent, depending on whether the U1 chip was actually plugged in or
not.
Happily, the reflow job turned the trick and saved the day. The BAL command
now works, U5 is awake, R1 nulls beautifully, and PTT now works as it
should. Isn't it amazing what the Burdick crew's designs can do, especially
when you turn on the DC supply to them?
The lesson to be learned? If anything looks a little suspicious during
construction, take the time RIGHT NOW to either FIX IT, or be CERTAIN
otherwise that you are NOT leaving the door open for later trouble! Mojo
can't always save the day...
In this case I was VERY lucky to be able to repair the invisible broken U1
socket pin by reflowing the joint. Had I not been so lucky, removal of the
socket would have been VERY TOUGH, if even feasible. I'd likely become the
owner of two KSB2s, one working in the K2 and the other bronzed living on
the fireplace mantel.
Thanks to all for your comments and help.
Steve Banks K0PQ
K2 S/N 1599
++++++++++++++++++++++++++++++++++++++++++++++++++++
Date: Sat, 21 Apr 2001 16:51:16 -0400
From: "Don Wilhelm"
Subject: Re: [Elecraft] KSB2 card inoperative..follow-up message
Steve,
You might want to make a mental memo: If you must remove a large socket (or
an IC) the way to do it is to clip the leads of the socket or IC on the top
side of the board and remove the remains of the pins one at a time.
Always remember that the PC board containing the rest of your work is far
more valuable than the most expensive IC mounted on it - saving the board is
always first priority.
73,
Don Wilhelm -Chapel Hill, NC W3FPR home page: http://www.qsl.net/w3fpr/
QRP-L # 485 K2 SN 0020 mailto: w3fpr at arrl.net
++++++++++++++++++++++++++++++++++++++++++++++++++
Date: Mon, 30 Apr 2001 23:36:27 -0600
From: Kevin Ferguson
Subject: RE: [Elecraft] Added SSB, now RX is weak. BINGO!
Thanks to all that emailed me with words of encouragement, and advice.
Even though most of the advice was things I already checked, it was good
to know I hadn't overlooked anything obvious.
So what was it you ask?
Well I grounded out U12-5 (AGC input to IF amp)
and got my ears thumped. Voltmeter showed it was
sitting at ~4.3V. I checked U2-1 (AGC buffer)
which only had ~3.6 V on it. Hmm, ~.7
across R4 (5.6K) is around 1.5 milliamps...
which seems a little much for just a control signal.
I scrubbed around U12-5 with a ethynol soaked Q-tip, and
the voltage dropped to 3.9V. Voila! gain is back to normal.
Apparently the flux in the solder wick (tech-spray pro-wick) which
I used to remove W3 migrated, and created a leakage path to some
higher voltage point, raising the AGC input to the IF amp, thus
killing the gain by about 12dB. Only a couple of S units, but
my ears were SURE there was a difference.
After the washdown, I again grounded U12-5, and could only _just_
detect an increase in noise (with preamp on, no ANT, AGC off).
indicating that U2B is biased just above the edge of AGC
cut-in, for smooth AGC action. Interesting that there is still
around .3 V drop across R4.
1937 is back....Yes!
I know Wayne and Eric say that flux remover is not required,
but they might add a caution about solder-wick in the manual.
The wick NEVER indicates what sort of flux it is saturated with,
and in my case it must be fairly aggressive. I think I'll be scrubbing
off the residue after de-soldering from now on.
Tnx agn to all
- -73-
ko0b
++++++++++++++++++++++++++++++++++++++++++++
Date: Sat, 2 Jun 2001 19:33:03 -0700
From: "Ron D' Eau Claire"
Subject: RE: [Elecraft] KSB2 questions
Mike wrote:
> I'm using ... Radio Shack $20 CB microphone, # 21-1172. Since
> the audio line in the mic is switched by the PTT button, I have to jumper
> this line internally (in the mic) to be able to do the carrier
> balance test
> & adjustment, ... In SSBA BAL mode, I get good S-meter readings
> that jump around as expected with my voice, and can easily & clearly hear
> my voice on the rig's speaker (& headphones, of course). I don't
> think I'm
> reducing the carrier as much as it could be, as I'm getting readings of
> around .5 v minimum on USB and .8 v on LSB off my Fluke 87 meter
> & RF probe...
> when I switch to another SSBA mode (e.g. 2) that I can key the rig
> (and the quieting on another receiver), but there is no audio and no
> S-meter indication of RF or ALC on the K2. Ideas? I read that in BAL
> mode, the adapter's output goes directly to the rig's IF. Now, if I can
> hear myself in this mode, why can't I in the regular operating modes?
>
Mike, you do NOT want any audio passing through the rig when you do the
carrier balance. That residual voltage may be due to random noise that your
mic is picking up. I jumpered by PTT to ground with no mic and that gave me
a very low "fine carrier" balance adjustment. I don't recall what it was
exactly, but I used an r-f voltmeter like you did.
In the manual where they suggest using another receiver, I believe that what
you would be looking for is the steady tone of a heterodyne of the carrier,
not the modulation. And then you adjust the fine balance to make that level
as low as possible.
You mention "quieting" on another receiver when you key the mic. "Quieting"
is an F-M phenomenon that refers to the background noise in a receiver being
quieted when an f-m signal is sufficiently strong. SSB doesn't work that
way. Ideally, you would be completely unaware of any change when you key the
mic in SSB if you don't have any audio being transmitted. The idea is that
the carrier is completely suppressed (balanced out) and so with no audio
modulation there is no r-f output. Since the carrier is really only 30 or 40
dB below peak output, you WILL hear the carrier on a receiver sitting close
by - and it may tend to 'quiet' the background noise but you should also be
hearing a big loud heterodyne unless you have both rigs zero beat on the
same frequency. In that case, you might hear something that sounds like
'quieting' if the other receiver's AGC is still reacting to your signal.
Normally it won't.
As for the lack of audio in 'normal' operation, try injecting some audio
(from any handy source such as the phones output from a radio, etc.) to C34
input (or through a cap of any convenient value) to the junction of R15/R14
and see if you get some output in SSB mode. That would tell you if the
problem is in the mic side of the audio or the compressor side. It sounds
like you aren't getting much into the rig from the mic. Putting some audio
in directly to the board will tell you if you have an open circuit through
the configuration jumpers or elsewhere in the mic line.
I use the same mic as you have, and it works quite well. I did raise the
value of R14 to 5.6K because the audio level was marginal on 10 meters with
the original 1k resistor.
Ron AC7AC
K2 # 1289
+++++++++++++++++++++++++++++++++++
Date: Mon, 25 Jun 2001 09:17:10 +0000
From: Marteinn Sverrisson
Subject: [Elecraft] K2 S-meter changes after SSB adapter is installed
After building my K2, I calibrated the S-meter and it worked as expected
with the LOW setting around 175 and the HI setting around 25.
But.., when I inserted the SSB adapter
I noticed that the S-meter was showing S-2 with no signal.
The S-meter now shows 2 S-units on USB on bands 1.8 to 18.1 and
LSB on 21 and above. ( 1 S-unit on LSB on 1.8 to 18.1 and USB on 21+).
Normal on other settings.
Recalibration of the S-meter shows there is a difference,
now the LOW setting is around 185....
I suspected this to be rf leakage from the bfo osc, through the SSB
adapter PCB.
I can reduce (but not eliminate)
the leak by inserting a vertical grounded screen
(made of thin pcb with the copper side in contact with X5 and X6, insulated
otherwise so not to short other connections)
between the SSB adaper PCB and X5 and X6,
extending from the crystals to U11.
Is this a known problem?
73 de
TF3MA
+++++++++++++++++++++++++++++++++++
Date: Mon, 25 Jun 2001 21:02:28 -0600 (MDT)
From: Schwindt
Subject: [Elecraft] More S-meter/SSB board questions...
Hi all,
I too have some questions about the behavior of the S-meter and the SSB
board.
Depending on whether I go through the S-meter calibration in SSB
mode or CW affects what settings I get for S-LO and S-HI. For SSB I get
S-LO=185 and S-HI=24. On CW mode I get values of 197 and 20 (the numbers
for CW mode vary slightly with the filter selected--both decreasing by 1
for the narrowest filter).
My question is the same as Marteinn's, i.e. is this behavior normal or
indicative of something out of whack on my K2? It's probably worth
mentioning that I have installed the SSB filter passband mod.
Thanks and 73's
Nick
KC0BGA
++++++++++++++++++++++++++++++++++++
Date: Tue, 26 Jun 2001 11:12:15 -0700 (MST)
From: Gary Hembree
Subject: [Elecraft] Re: Elecraft] More S-meter/SSB board questions...
The amount of noise presented to the IF amp is dependent on the filter
bandwidth, hence the variation in s-meter calibration. There may also be
BFO leakage involved, which will vary depending on the mode (CW vs SSB)
and filter setting.
My K2 behaves in the same way as yours. Don't worry, the AGC will still
work just fine. An S-meter is more of a visual indicator than a
measurement tool on any receiver that costs less than $5K.
73
Gary, N7IR
DM43bi
++++++++++++++++++++++++++++++++++++
Date: Tue, 3 Jul 2001 16:03:43 EDT
From: K9ut at aol.com
Subject: [Elecraft] K2 Mic Gain Mod
I recently made the mod to the ssb adapter (N0SS) ,changed R1 to 5.6k, and
now the vox has adequate gain and it also has given more punch to the signal
without any distortion! Have been using a old Shure mic here and all reports
have been good. Also placed a fibreglass mesh (screen) under the spkr to keep
out any debris. Hope this is helpful !
72, 73 K9UT #1273
+++++++++++++++++++++++++++++++
Date: Wed, 4 Jul 2001 08:46:36 -0700
From: "Ron D' Eau Claire"
Subject: RE: [Elecraft] C180 To pull or not
Alan, W1HYV, asked:
> Hi:
> I recall something about pulling C180 on the RF board if you are going
> to use the SSB adapter. Is my memory failing because I can't find any
> reference to it.
>
C167 is the only cap I know of that gets pulled when the SSB adapter is
installed.
You may be thinking of the modification to improve the 'flatness' of the 2nd
i-f filter. That involves changes to C180. It is a good mod to make whether
one uses cw or ssb, but it's effect is greatest for improving the quality of
ssb reception.
Ron AC7AC
K2 # 1289
++++++++++++++++++++++++++++++++++
Date: Wed, 04 Jul 2001 09:25:49 -0700
From: Vic Rosenthal
Subject: Re: [Elecraft] C180 To pull or not
Ron D' Eau Claire wrote:
> You may be thinking of the modification to improve the 'flatness' of the 2nd
> i-f filter. That involves changes to C180. It is a good mod to make whether
> one uses cw or ssb, but it's effect is greatest for improving the quality of
> ssb reception.
I also remember that simply removing this capacitor was suggested in the past,
but its effect -- if I recall correctly -- was to broaden the two-crystal filter
which follows the main filter. This filter's function is to sharpen the skirts
of the overall response, and for CW bandwidths I think it was OK as originally
spec'd. I suspect that just removing C180 would NOT be good for CW.
This is not the same as the more recent Elecraft-approved mod which includes a
transistor to change the characteristics of this circuit when switching between
CW and SSB, and which is probably what you are referring to. I believe that the
newer mod doesn't have any effect on CW, though.
73,
Vic, K2VCO
Fresno CA
++++++++++++++++++++++++++++++++++
Date: Wed, 4 Jul 2001 10:06:59 -0700
From: "Ron D' Eau Claire"
Subject: RE: [Elecraft] C180 To pull or not
Vic, K2VCO, wrote:
> This is not the same as the more recent Elecraft-approved mod
> which includes a
> transistor to change the characteristics of this circuit when
> switching between
> CW and SSB, and which is probably what you are referring to. I
> believe that the
> newer mod doesn't have any effect on CW, though.
You are right. I do remember seeing some comments about simply taking that
cap out, but I think it would degrade the filter performance. The little
transistor switch is a very simple and effective mod.
That is the mod I did on my K2 initially for better SSB reception but I
found that it made listening to CW much more pleasant for me using the wider
bandwidths. The 'tilt' in the bandpass caused by the original filter made
the background noise low pitched on some bands and irritatingly high pitched
on the other bands.
Ron AC7AC
K2 # 1289
++++++++++++++++++++++++++++++++++
Date: Sat, 28 Jul 2001 11:42:39 -0400
From: "Francis Belliveau"
Subject: Re: [Elecraft] SSB no mic audio
On: Saturday, July 28, 2001 11:03 AM
wrote:
> I just finished the SSB adapter...
> If I'm understanding the manual correctly, I should be able to hear myself
> talk when I set SSBA to BAL.
I ran into a similar problem and discovered that the Push-to-Talk button on
the microphone shorted out the mc element when not being pushed. My
solution was to disconnect the PTT button from the K2 so that I could push
it without the K2 exiting BAL. That allowed me to pass the test and check
things out properly.
Fran, KA4FRH
K2 s/n 314
+++++++++++++++++++++++
Date: Tue, 04 Sep 2001 22:26:39 -0700
From: "John Grebenkemper, KI6WX"
Subject: Re: [Elecraft] KSB2 modifications for PSK
Eduardo;
My understanding is that the resistor value changes and capacitor value
change will be incorporated in the next revision of the KSB2 kit. I don't
believe that Wayne is planning any other changes. Putting a 5.6K resistor
across R1 is my idea to avoid clipping in the NE602 if you have plenty of
mike output, or you use PSK31 and want to leave compression enabled. Don't
do it if you have a low output mike because you might not have enough drive
to get full output on the higher frequency bands. Except for PSK31, doing
this change is not very critical because any out of band audio
intermodulation distortion will be removed by the SSB filter.
- -John
KI6WX
- ----- Original Message -----
From: "Eduardo Jacob"
To:
Sent: Tuesday, September 04, 2001 6:12 AM
Subject: [Elecraft] KSB2 modifications for PSK
> I will begin mounting soon the KSB2 module. I have read the modifications
> proposed by KI6WX, they seem to be fully approved by Elecraft, I also read
> some days ago that somebody stated that these mods will be included in new
> versions of the board, so the question is: should I directly make the mods
> to my board? I also understand that in the general case the addition of a
> 5.6K resistor across R1 is not recomended.
>
> Regards
>
> Eduardo/EA2BAJ #2061
+++++++++++++++++++++
Date: Mon, 17 Sep 2001 17:43:22 -0700
From: Eric Swartz WA6HHQ - Elecraft
Subject: Re: [Elecraft] K2 Mic
Hi Steve,
Hi Steve,
The difference you note on SSB RX response on the higher bands is present
primarily on RX, not TX, as it is a result of the 2nd IF crystal filter which is
not used on SSB TX. In general SSB TX frequency response stays pretty close to
the same regardless of the mixing scheme if you have set up the BF1t settings
equally for LSB and USB on the same band.
Prior to the MH2 I used a Kenwood microphone from my TS-50 on the K2 with no
problems. I suspect what you might want to do is adjust BF1t on both USB and LSB
(say on 40M) to equalize your TX audio. Since we flip the mixing scheme on the
upper bands as you noted the LSB settings from the lower bands become the USB
settings on the upper bands and the USB settings are used for LSB. If your BF1t
settings were set up for different USB and LSB frequency responses this may
account for your problem.
In general I adjust the BF1t TX audio settings by transmitting with the K2 into
a dummy load while listening on another RX. Ideally it is best to record the
audio as it is hard to discern TX audio differences by talking and listening at
the same time. I use my PC sound card to record samples and compare them for
different BF1t settings.
73, Eric WA6HHQ
You can change the
Steve and Anne Ray wrote:
>
> I know this subject has probably been over done, but anyway. I am using a
> Kenwood MC50 mic with my K2 and get reports that the audio is a little soft.
> This is mainly noticeable on 20 and 17 meters, just does not punch through.
> Naturally I run USB on 20 and 17.
>
> I have run spectrogram and also looked at the rf output with my scope with
> various audio frequencies and the K2 is lacking higher frequency response on
> USB on 80-17, this agrees with the spectrogram plots. Likewise the high
> frequency response is down on LSB on 15-10 meters. This agrees with the
> Spectrogram plots and rf output. So there is plenty of audio on LSB on 80,
> 40 meters where you need it, and on 15-10 meters on USB. Unfortunately the
> response is down on 20-17 meters on USB. This makes sense with the way the
> mixing scheme works.
>
> The above is not serious and I can live with it, but if I can improve on it
> I sure would like to.
>
> I like having a desk mic so the MH2 is out of the question. I have modified
> my SSB board to have the 10K resistor at R14. I am now considering putting
> a Heil HC4 or HC5 element in the Kenwood MC50.
>
> What is the general opinion is it worth upgrading to the Heil element and if
> so what is the preferred one. I am not a DXer, but do want the signal to
> have some punch.
>
> Thanks
>
> 72,
>
> Steve K4JPN
> Elecraft K2 S/N 1422
+++++++++++++++++
Date: Mon, 22 Oct 2001 22:15:08 -0400
From: "Randy Hargenrader"
Subject: [Elecraft] SSB Filter Setup Suggestion
Elecrafters,
I recently installed version 2 firmware in my K2 (finally!). While I
was in there I went ahead and did the CW filter grounding
mod. Of course, this then led to doing the Spectrogram thing
and while I was set up to do that, I did the SSB filters, also.
While I was adjusting the "narrow" SSB filters I decided to set
up FL4 as the PSK one and center it on 1KHz. For FL3, my
"really narrow SSB filter" I remembered something from my
days in mobile telephone. (Its funny how your brain will latch
onto the most obscure stuff!)
Motorola engineers/scientists (whatever) had found that there
were two components to just about every voice, no matter what
language or sex, or whatever, that were universal. These were,
1200Hz and 7Hz. 7Hz is the rythmic pattern in most speech
and 1200Hz is the common frequency in most human voices.
Using this information, (the 1200Hz component) I centered
FL3 on 1200Hz. This made the filter actually usable for SSB,
and gave me another tool to deal with QRM.
73,
Randy WJ4P
+++++++++++++++++++
Date: Mon, 29 Oct 2001 11:02:58 -0800
From: "Lyle Johnson"
Subject: RE: [Elecraft] K2 2nd. filter mod (improving SSB receive)
Hello Bob!
There is more to it than changing a cap.
See http://www.elecraft.com/Apps/new_fil_docs/k2_2nd_xfil_ssb_mod.pdf for
details.
73,
Lyle KK7P
> What is the part number and value of the capacitor on the RF board that
> is changed to improve SSB receive?
> Bob Abell, VE3XM
> K2 S/N 2062
+++++++++++++++++++=
Date: Mon, 29 Oct 2001 16:15:42 -0600
From: Tom Hammond =?iso-8859-1?Q?N=D8SS?=
Subject: RE: [Elecraft] K2 2nd. filter mod (improving SSB receive)
> > What is the part number and value of the capacitor on the RF board
> > that is replaced by a 120 pf capacitor to improve SSB receive?
>
>It's C180 on the RF board - either a 10 pf or 20 pf cap depending upon the
>age of the K2. But it is NOT just 'replaced'. The mod involves installing a
>transistor switch as well. You'll need a 120 pf cap, a small signal
>switching transistor (2N2222, 2N3904, etc.), a 0.l uf cap and a 3.3k Ohm
>resistor.
Actually, it's C182 that's being paralleled. C180 is REMOVED, regardless.
Tom N0SS
++++++++++++++++++
Date: Mon, 29 Oct 2001 22:59:56 -0500
From: Dave Gingrich K9DC
Subject: Re: [Elecraft] K2 2nd. filter mod (improving SSB receive)
At 14:49 10/29/2001 -0800, lhlousek wrote:
>Actually, the way I understand it, C180 is not replaced. It is removed. The
>120 pf cap is switched in elsewhere in the circuit by the added transistor
>only
>when the OPT1 filter (on the SSB option) is switched in. This suggests that
>simply removing C180 on K2s that don't have the SSB option would improve the
>flatness of the RF board filter for CW and SSB. The other components would not
>be needed.
>
>Anybody ever done this and what, if anything, would be the down-side?
I simply removed C180 and did not add the switched in extra components. I
then realigned L34 several times using Spectrogram, and settled on the best
balance (perhaps a compromise) between LSB and USB. On the other hand, my
filter response before the mod was not as bad as those shown in Tom's
paper. I have it perfect now, no difference between USB and LSB
at all.
Spectrogram was a big help in setting L34 correctly. You also could use the
spectrum analyzer function in HamScope or even a PSK waterfall display, but
the dual markers in spectrogram are handy.
++++++++++++++++
Date: Tue, 30 Oct 2001 11:16:28 -0800
From: "Ron D' Eau Claire"
Subject: RE: [Elecraft] K2 improving SSB receive
Bob, VE2XM asked:
> Does this mod work in the (1st Xfil)
> position of the Xfil selection button?
> The instructions would seem to imply it would only work when (2ndXfil)
> is selected.
I think you are reading 2nd Xfil and thinking that means the XFIL 2 position
of the variable bandwidth filter, Bob. It's just a bad choice of words in
the Application note.
There are filters at two places in the K2. This is like many
high-performance superhetrodyne designs. The first filter is at the input to
the i-f strip where the selectivity of the receiver is established. Then the
i-f signal is amplified in U12 and then goes through a second, wider, filter
at the output of the i-f strip. The second filter helps roll-off noise
generated in the i-f.
The first i-f filter is the variable bandwidth filter. The second i-f filter
is fixed.
The problem is in the second, fixed-bandwidth, i-f filter. It has a
pronounced 'tilt' in its bandpass characteristic. The mod reduces that tilt.
When the Application note refers to 2nd XFIL, it means this second i-f
filter, not XFIL 2 position in the variable bandwidth filter.
So the mod affects any setting of the variable bandwidth filter you use.
Ron AC7AC
K2 # 1289
+++++++++++++++++++
Date: Thu, 08 Nov 2001 12:57:27 -0600
From: Tom Hammond =?iso-8859-1?Q?N=D8SS?=
Subject: Re: [Elecraft] R2 - R14 swap SSB adapt.
I've been recommendong ONLY the R14 mod since it was mentioned a while back
(by KI6WX, I believe) that changing changing R2 as well tends to overdrive
the B/M.
Tom
Phil Wheeler (W7OX) wrote:
>Rather than a swap (I'd already built it), I changed only the resistor
>on the input side .. and that seemed enough.
>
>Ron D' Eau Claire wrote:
>
> > Several ops observed that doing the swap increased the audio level to the
> > balanced modulator by decreasing the amount of R2 from 5.6 k to 1.0 k and
> > that MIGHT result in too much audio at the modulator.
> >
> > Sounds like it's worth investigating, based on your experience.
++++++++++++++++
Date: Thu, 08 Nov 2001 18:22:29 -0800
From: "John Grebenkemper, KI6WX"
Subject: Re: [Elecraft] R2 - R14 swap SSB adapt.
My recommendation was to not reduce R2 if you enable speech compression.
With speech compression on, the SSM2165 wants to drive to an output level
that will cause clipping in the NE602. With R2 reduced, this clipping
becomes even worse and can cause the audio quality to degrade. Even without
changing any resistors, you may find that enabling speech compression can
get enough gain to drive the K2 to full power output on SSB, as long as your
mic has enough output to get above the compression floor of the SSM2165.
- -John
KI6WX
> I've been recommendong ONLY the R14 mod since it was mentioned a while
back
> (by KI6WX, I believe) that changing changing R2 as well tends to overdrive
> the B/M.
>
> Tom
+++++++++++++++++++
From: "Dan Barker"
To: "Elecraft"
Date: Wed, 20 Feb 2002 08:11:33 -0500
Subject: [Elecraft] KSB2 Missing Errata
I just finished the final tests of my new KPSK2, er ah, KSB2, and there =
are a couple things the book and errata missed. These should be added.
Firstly, the book says "with some mics it is necessary to connect 5V to =
AF through a resistor." The MH2 mic is listed in table 2 with no notes. =
It needs a note to place a 5.6K resistor across the jumpers AF and 5V. =
By the time you get to the instructions that involve plugging in the mic =
(and finding the resistor hidden it it's box), you've buttoned up the =
rig. Have to remove the FP, two jumpers, solder a resistor between them, =
and continue. Not very time consuming, but since this is the "party =
line" mic, it ought to go in flawlessly following the instructions =
directly.
Secondly, discovering there were Elecraft Instruction with the Heil =
Package (I thought), required getting the rig to fail some tests. =
Nothing looked amiss. All the volts were bang-on (even the switching =
Diodes) except U1 pins 21, 22, 23 and 24. But they all go to U3, and U3 =
was bang-on too. Odd. I couldn't make heads or tails of it. Tracing the =
audio (there was none) led me to the hidden resistor and instructions in =
the Heil packaging. Just as the sitching diodes voltage measurements =
specify conditions to be valid, we should ADD to the IC voltage =
measurement conditions "Mic plugged in AF baised to X.X volts" or =
whatever is required to get those measurements to match.
Thirdly, thanks for the jumpers, however, there was no hint of them in =
the book, and I'd already rummaged for enough (took a while - pulled 9 =
off an old 486 - hope I never need it!) by the time I found them in with =
the mystery resistor. A note that they are included (or including them =
with the KSB2 instead of the MH2) would have saved me a bunch of time.
As usual, all the suggested filter settings are off 300 to 500 Hz. I'll =
get it tuned back up, but I wonder if there is something different in my =
rig? Ah well, another post.
Dan.
++++++++++++++++++++
From: "Dan Barker"
To: "Elecraft"
Cc: "Steve & Anne Ray"
Date: Mon, 25 Feb 2002 17:39:48 -0500
Subject: [Elecraft] SSB Filters
Failing miserably to get my K2 sounding right on my own, I grabbed the =
telephone and called Elecraft. I had LSB sounding OK, and USB off in =
left field. None of my numbers were within 400 Hz of the "book" values. =
Gary said that was fine.=20
Gary talked me through the procedure for a K2 with recent firmware and =
the KSB2 adapter installed.
a) Bend C180 back and forth until it breaks off, and discard.=20
b) Fire up Spectrogram; and set a marker at 400 and 2200 Hz.=20
c) Move the FL1 BFO freq. until it's balanced between the marks.=20
d) Repeat for the other sideband.=20
e) Diddle L34 to flatten the top of the USB response, but not so far as =
to screw up the LSB response.
f) Repeat centering the response curves if necessary.
My results below:
USB
Picture suppressed on reflector, see =
http://www.visioncomm.net/ssb.html
LSB
Picture suppressed on reflector, see =
http://www.visioncomm.net/ssb.html
I just spend about an hour on SSB with Steve in GA, and he says both =
Sidebands sound FB, and the same. Cool!
So, what's this about a flattening mod? Doesn't really look like one is =
needed.
Dan / WG4S / K2 #2456, KAT2, K160RX, KIO2, KSB2
PS: Now, How do I get on PSK? The MH2 ain't gonna cut it! I'm a gonna =
need some WIRE! (who ever called this hobby wireless? - They're nuts!).
+++++++++++++++++++++
From: "Dan Barker"
To: "Elecraft"
Subject: [Elecraft] SSB Filters
Date: Tue, 26 Feb 2002 07:09:58 -0500
Ron: Now you've got me wondering what damage I might have done to CW. =
Any way to measure the S/N at my current setting? I could then peak it =
and see what I'd lost. If it's just db between that birdie at 7mhz and =
the noise floor, I can take that number off Spectrogram. Might need a =
little amplification to get a good reading.
I'd like to know what the SSB audio cost me on CW.
Dan
-----Original Message-----
From: Ron D' Eau Claire [mailto:rondec at easystreet.com]
Sent: Monday, February 25, 2002 10:33 PM
To: Dan Barker
Subject: RE: [Elecraft] SSB Filters
True enough, Dan.
The "flattening mod" was more for receive than transmit. My K2 sounded
absolutely tinny on one sideband and bassy on the other until I put it =
in. I
was able to get it "flat" by adjusting the coil, but that really =
compromised
the signal/noise ratio on CW. That's when Wayne or Eric came up with the
transistor switch mod.
I suspect the need for it varies a bit with each radio, since these =
filters
are made up of discrete xtals.
I wanted to know because next time someone asks about the weird SSB =
audio on
the reflector, I'll suggest that they consider doing what you did as =
well.
Thanks,
Ron AC7AC
> -----Original Message-----
> From: elecraft-admin at mailman.qth.net
> [mailto:elecraft-admin at mailman.qth.net]On Behalf Of Dan Barker
> Sent: Monday, February 25, 2002 7:15 PM
> To: Elecraft
> Subject: [Elecraft] SSB Filters
>
>
> Ron:
>
> You are absolutely right, it's just build the thing, and remove
> the 10 pf cap, and twist some knobs (one LARGE, several small). I
> read about the "flattening mod", but the Spectrogram came out so
> nice without it, I don't really see the need. The guys on the
> receiving end don't seem to hear the need either.
>
> My rig is stock except for the sidetone cleanups (not very clean,
> but at least better) and C180 being pulled. The "trick" was not
> to worry that my numbers were so very far from the examples (like
> 400-600 Hz) in the book and in diddling L34 by eye, not ear.
>
> Dan / WG4S / K2 #2456
>
> -----Original Message-----
> From: Ron D' Eau Claire [mailto:rondec at easystreet.com]
> Sent: Monday, February 25, 2002 8:20 PM
> To: Dan Barker
> Subject: RE: [Elecraft] SSB Filters
>
>
> Hi Dan:
>
> By your description of removing C180, I take it you did not put
> the "filter
> flattening" mod in that is provided as an Application Note on the =
Elecraft
> Reflector.
>
> Just curious, because you managed to get a very nice looking response
> without it if that's so.
>
> Wayne/Eric announced almost two years ago that the mod would
> become part of
> the r-f board in future releases, but I've not yet seen it hit the =
street.
> They may have re-thought the idea.
>
> Ron AC7AC
> K2 # 1289
+++++++++++++++++
From: "Dan Barker"
To: "Elecraft"
Subject: FW: [Elecraft] SSB Filters
Date: Tue, 26 Feb 2002 10:47:40 -0500
All other doc bitches aside, you gotta love the PDF's. If you can't find =
a part on the schematic, or in the text, the FIND function can. I wish =
I'd had my HW-101 doc on PDF back in the 70's. (Of course, my TRS-80 =
didn't have Adobe, darn).
Dan
-----Original Message-----
From: Ron D' Eau Claire [mailto:rondec at easystreet.com]
Sent: Tuesday, February 26, 2002 10:38 AM
To: Dan Barker
Subject: RE: [Elecraft] SSB Filters
Y'know. that's a GOOD point, Dan.
Your question got me to go take a look at the documentation.
The Elecraft Application Note dated 1 June, 2000 "Eliminating the =
Frequency
Roll-Off On One End of the K2 SSB Filter" does say that one way to =
"flatten
out" the apparent response of the SSB Option filter is to, "Adjust L34 =
until
the passband of the filter appears to be more uniform..." and then it =
goes
on to say, "Unfortunately...the overall signal-to-noise ratio of the K2
receiver will be compromised."
HOWEVER... that is with C-180 still in the circuit. The mod involving =
the
transistor switch removes C-180 from the circuit (as you did) and adds =
120
pf in parallel with C182 only during SSB operation. Does simply removing
C-180 without using the transistor switch to add the 120 pf capacitor to =
the
circuit work as well? Perhaps. I've not see a peep about it on the
reflector. So I can't say whether the procedure Gary gave you would have =
the
same negative effect on the S/N that the Application Note predicts.
But you can check it. Just try setting L34 for best Signal-to-Noise =
ratio in
CW mode on a weak signal and see if that is a DIFFERENT setting from =
where
it is now. To do that the instructions (in the above application note) =
say
to remove the antenna from the rig and turn on the pre-amp, then tune in =
the
'birdie' they all have at 7 MHz. (This spurious signal is normally only
audible with the antenna disconnected.) Then the procedure says, "While
listening to the weak signal at 7000 kHz, adjust L34 for the best signal
strength and lowest noise. The best overall setting typically occurs at =
1-2
turns below the top of the can."
You can do that to see if the setting on L34 is different from where you
have it now.
I think I will post a question about whether the 120 pf cap is still =
needed
on the reflector.
I am a writer by trade, and have been becoming increasingly frustrated =
by
the morass of documents relating to MY particular K2 - option manuals,
application notes AND all the various changes to all of those that have
occurred over the past two years. Have a fat envelope of documents and =
it's
getting impossible to keep track of them.
And then they leave important stuff out of the documents. Case in point =
was
the issue of the tuning rate actually slowing down as one turns the K2
tuning knob faster that I brought up on the reflector recently. It =
turned
out that is "normal", if counter-intuitive, with the Rev. 2 firmware. It =
is
a performance compromise they accepted in order to get more accurate =
dial
calibration across the tuning range. But they forgot to mention it in =
the
documentation.
It's a very small team at Elecraft, and the sheer volume of material is
starting to overwhelm them too, from the looks of it.
Ron AC7AC
+++++++++++++++++
Reply-To:
From: "Ron D' Eau Claire"
To:
Subject: RE: [Elecraft] Spectogram
Date: Sat, 23 Mar 2002 16:42:17 -0800
> Just finished K2 kit 2521 and would like to use Spectogram to align
> it. Is there a step by step "how to" listed somewhere?
> Dudley KC5SDF
Go to http://www.elecraft.com, then click on "Builder Resources" on the menu
on the left side of the screen.
On the Builder Resources page look under "Main Topics" on the main page and
click on "Application Notes". That will take you to the page with "Elecraft
Application Notes" at the top.
Scroll down on the left side of the main page (with the white background)
and you will find "K2 Filter Adjustment and Mod Articles". Click on that and
you will find yourself presented with a series of articles on downloading
Spectrogram and using it to align your filters for either CW or SSB.
IF you are setting up your SSB filters too, PLEASE be sure to run an actual
on-air audio quality check, feeding a dummy load and listening to yourself
on an auxiliary receiver (I find it most useful to first tune myself in,
then record the audio so I can listen closely). If you can't do that at
LEAST have a buddy give you a critical audio check.
Last night I was spooking 40 meters and heard a fellow in QSO on SSB who had
simply awful audio. The guys he was working said it sounded "pinched", which
was a pretty good description. It sounded like his frequency response was
all of perhaps 500 Hz to a bit over 1000 Hz. He explained that he was
running a K2 with a brand new MH-1/Heil mic and "put in all the mods"
Elecraft recommended. Everyone was being very polite but clearly unimpressed
with the sound of his signal.
I have no idea if it was the mic or if he had the filters misaligned.
Considering the reported quality of that mic, I'd suspect the latter.
One thing was for sure- he had NOT checked his own audio "on the air".
Ron AC7AC
K2 # 1289
+++++++++++++++++++
From: "Don Brown"
To: "Elecraft"
Subject: Re: [Elecraft] Aligning KSB2 with O'scope
Date: Mon, 25 Mar 2002 15:25:12 -0600
HI
I use a OHR wattmeter on the 100 mW range but you could use a scope the s=
ame way. Connect the K2 antenna connector with a BNC cable through a 50 o=
hm terminator to the scope and adjust for minimum RF out. If you don't ha=
ve the feed through type of terminator use a BNC Tee at the scope and con=
nect the cable and terminator to the Tee. If you have one of the 50 ohm d=
ummy loads made up of resistors just clip the scope probe on to the cente=
r of the connector pin in the load or one of the resistors.
Don Brown
KD5NDB
----- Original Message -----
From: cwbybee at attbi.com
Sent: Monday, March 25, 2002 2:37 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Aligning KSB2 with O'scope
I am about to build the KSB2 and since I don't have
another receiver (at least not one with an S meter), I
intend to use my O'scope. Where would be the best place
to probe when adjusting the carrier balance?
++++++++++++++++